WOMS
P code powertrain Medium severity

P0802 Transmission Control System MIL Request Circuit / Open

The OBD2 code P0802 indicates a malfunction in the transmission control system, specifically related to an open circuit or fault in the circuit that requests the Malfunction Indicator Lamp (MIL) to be activated

Definition

The OBD2 code P0802 indicates a malfunction in the transmission control system, specifically related to an open circuit or fault in the circuit that requests the Malfunction Indicator Lamp (MIL) to be activated

Common causes

  • Faulty transmission control module (TCM)
  • Open or shorted wiring in the MIL request circuit
  • Poor connections or corroded terminals
  • Faulty engine control module (ECM)
  • Malfunctioning transmission range sensor
  • Defective transmission fluid temperature sensor
  • Issues with the vehicle's power supply or ground connections

Common misdiagnoses

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or shorts in the circuit
  • Faulty Engine Control Module (ECM)
  • Malfunctioning sensors (e.g., throttle position sensor)
  • Transmission fluid issues (low fluid, contamination)
  • Faulty shift solenoids
  • Issues with the vehicle's battery or charging system
  • Problems with the OBDII connector or communication issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors related to the transmission control module (TCM) and the MIL request circuit. Look for signs of damage, corrosion, or loose connections

  4. 4. Pay special attention to any connectors that may have been disturbed during maintenance or repairs

  5. 5. Test the MIL Request Circuit

  6. 6. Use a multimeter to check the continuity of the MIL request circuit. If the circuit is open, you will need to trace the wiring to find the break

  7. 7. Check for shorts to ground or power in the circuit

  8. 8. Check the Transmission Control Module (TCM)

  9. 9. Ensure that the TCM is functioning properly. If you suspect a fault, you may need to test or replace the TCM

  10. 10. Check for any software updates or reprogramming that may be required for the TCM

  11. 11. Inspect the Fuse

  12. 12. Check the fuse related to the transmission control system. A blown fuse can cause the circuit to be open

  13. 13. Examine the Ground Connections

  14. 14. Ensure that all ground connections related to the TCM and transmission system are clean and secure. Poor grounding can lead to various electrical issues

  15. 15. Check for Fluid Issues

  16. 16. Inspect the transmission fluid level and condition. Low or contaminated fluid can affect transmission performance and may trigger codes

  17. 17. Perform a System Reset

  18. 18. After addressing any issues found, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  19. 19. Consult Technical Service Bulletins (TSBs)

  20. 20. Check for any TSBs related to your vehicle's make and model that may address known issues with the transmission control system

  21. 21. Seek Professional Help

  22. 22. If you are unable to resolve the issue after performing these steps, it may be best to consult a professional mechanic or technician who has experience with transmission systems and OBD-II diagnostics. By following these steps, you should be able to identify and address the underlying issue causing the P0802 code